A typical usage case could be to make it so that a template only adds a category when not on a template page. Thus not adding the template itself and other templates that are built with it to the category. Like this:

{{template other | | [[Category:Some maintenance category]] }}

Note that in the example above the "template" parameter was left empty.

No matter on what kind of page the code above is used it will return this:

Template page text

You can make it so your template also understands the demospace parameter. That means you can demonstrate the different appearances of your template in the documentation for your template. Then do like this: